Castor oil composition



Patented Mar. 17, 1936 2,034,405 CASTOR'OIL COMPOSITION Frederick H. Macmren,

signor to Standard Oil Company,

Calumet City, 111., as-

Ghicago, Ill.,

a corporation of Indiana No Drawing. Application March I, 1932,

. Serial No. 597,407

5 Claims.

This invention relates to a castor oil composition and it pertains more particularly to a method for dissolving castor oil in mineral oil to produce a permanent solution having desirable temperature viscosity characteristics.

Castor oil has long been recognized as a desirable ingredient in certain types of lubricants and fluid pressure transmitting mediums, but heretofore it has been impossible to incorporate the castor oil into a mineral oil without subjecting the castor oil to a heat treatment which is deleterious to its desirable physical and chemical properties. The object of my invention is to incorporate a considerable amount, for example to 25%, of castor oil in mineral oil without subjecting castor oil to high temperatures or to chemical decomposition; A further object is to provide a mixture of a mineral oil and castor ofl which will have a high viscosity index or, in other words, which will suffer a minimum change in viscosity with changes in temperature.

A further object is to provide a mixture of castor oil and mineral oil which will not separate at extremely high or low temperatures or on standing for extended periods of time.

In lubricating compressors for handling hydrocarbon vapors it is desirable that the lubricant be insoluble in vapor condensate, and an object of my invention is to provide such a lubricant. Other objects will be apparent from the following detailed description.

I have discovered that certain compounding agents, of which aluminum stearate is an example, have the peculiar propertyof solubilizing (forming an emulsion) castor oil and mineral oil, and I have found that the solution is so stable and so intimate as to constitute practically a true solution. For instance, I may incorporate 25 parts of castor oil in '12 parts of mineral oil by the use of three parts of aluminum stearate. The aluminum stearate is first incorporated in the oil at about 250 F., the mixture is cooled to about 100 F., whereupon it sets in the form of a jell, the castor oil is worked into the jell at low temperatures and the batch is worked or stirred at said temperatures toobtain the desired consistency. The invention will be more clearly understood from the following ferred embodiment.

An excellent high pressure lubricant may be made in accordance with the following formula:

Per cent Mineral oil 71 Castor oil 25 Aluminum stearate 4 detailed description of a pre- The mineral oil is preferably of the paraffinic type and of about the same viscosity as the castor oil. I prefer to use a by p ly erizing, in chloride, the unsaturated distillate from cracking paraffin wax according to the method described in the publication by Sullivan et al in Industrial and Engineering Chemistry-June 1931, page 604. A preferred oil has the following: characteristics:

Minimum gravity 30 A. P. 1. Minimum flash 470 F. Maximum pour point 20 F. Saybolt viscosity at 100 F 950 Saybolt'viscosity at 130 F 360-400 Saybolt viscosity at 210 F 85-90 Color 2 -3 Maximum Conradson carbon 0.2

I do not limit myself to synthetic mineral oils, however, and I have found that excellent results may be obtained by the use of highly paraflinic oils having about the viscosities above indicated. Mixtures with lighter oils are sufficiently stable for ordinary purposes.

In practicing my invention I mix the mineral oil with aluminum stearate or equivalent salt or soap and I heat the mixture to a temperature of about 350 F. If a heavy Pennsylvania lubricating oil is used instead of the synthetic oil, it may be necessary to heat the mixture to above 380 F. and, on the other hand, if a relatively low viscosity lubricant is used it may only be necessary.

to heat the mixture to about. 250 F.

Before adding the castor oil I preferably cool the solution of aluminum stearate to a temperature of about 100 F. I then slowly add the castor oil with stirring so that it is worked into the gel-like structure of mineral oil and aluminum stearate. The mixture has some of the properties of a grease, but the false body is broken down to a large extent by continued stirring or working so that the finished product may behave like a blended oil. If this product is subjected to high temperatures it may again take on this false body or gel-like structure, but such structure is readily broken down and is unobjectionable.

The mixture of castor oil and mineral oil, which is prepared as above described, may be chilled to low temperatures (-10 to 40 F.) or heated to high temperatures (300-400 F.) without causing the separation of castor oil from the mineral oil. Even a yearsstorage does not have any marked effect on the stability of this dispersion.

The amount of aluminum stearate is preferably synthetic mineral oil made the presence of aluminumv from 2% to 4% of the finished composition. One percent of aluminum stearate, or even one-half percent, may produce satisfactory dispersions for some purposes, but for most purposes they are not sufiiciently' stable. Larger amounts of aluminum stearate may be objectionable from the standpoint of cost and viscosity characteristics. A lubricant containing about 10% castor oil, 86% mineral oil and 4% aluminum stearate was centrifu'ged for five minutes at 300 R. P. M. and it was found that there'was practically no separation of the castor oil from the mineral oil.

I have described'a specific embodiment of my invention but I do not limit myself to the particular ingredients or proportions mentioned. Instead of aluminum stearate I may use zinc or magnesium stearate, or I may use aluminum oleate. Salts or soaps of this type which have the properties of aluminum stearate may be designated as solubilizing agents.

The term castor oil is used in the specification and claims of this application to define ordinary castor oil, 'or castor oil which has not previously been rendered soluble in mineral oils.

Also, it should be understood that a mixture of mineral oils of diiferent viscosities may be employed and that suitable fillers ordiluents may be used, as is well known in the lubrication art:

' I claim:

1. The method of dissolving ordinary castor oil in mineral oil without altering the physical or chemical properties of the castor oil, which comprises introducing a solubilizing agent of the class which consists of aluminum, zinc and magnesium stearates and oleates into the mineral oil at about A essentially of a stable homogeneous solution of I 5 to 25% of ordinary castor oil, 2 to 4% of aluminum stearate and the remainder a mineral oil.

4. A liquid lubricating composition which consists essentially-of a stable homogeneous solution of ordinary castor oil which has not been treated to render it soluble in mineral oil, mineral oil of about the same viscosity, and about 24% 01 aluminum stearate.

5. A liquid lubricating composition which consists essentially of a stable homogeneous solution of about 5-25% of ordinary castor oil which has not been previously rendered soluble in mineral oils, about 2-4% of a solubilizing agent of the class which consists of aluminum, zinc and magnesium stearates and oleates, and a mineral lubricating oil.

FREDERICK H. MACLAREN. 

